Vitamin D and Birth Outcomes in Pregnancy

Title: Vitamin D and Birth Outcomes in Pregnancy Purpose and Background/Significance: Vitamin D is essential for fetal growth and development and maternal wellbeing. Circulating maternal vitamin D (25[OH]D) serum levels in pregnancy influence birth outcomes, however, there is little evidence regarding the time in pregnancy when vitamin D levels have the greatest impact. Therefore, the purpose of this study was to examine the effects of maternal vitamin D throughout pregnancy. Theoretical/conceptual framework: David Barker’s theory of the Developmental Origins of Health and Disease provided the framework of the investigation of early pregnancy maternal vitamin D status as a predictor of birth outcome, influencing future health and disease. Methods: 25[OH]D was measured (EIA) in serum from nulliparous women (n=52) in each of three trimesters of pregnancy. We analyzed the relationship of 25[OH]D with pregnancy outcome measures including maternal early pregnancy weight, maternal weight gain across pregnancy, gestational duration, and infant birth weight (Spearman). The relationship between maternal circulating 25[OH]D levels and birth mode, gestational duration and infant birth weight were analyzed using regression models, controlling for maternal early pregnancy weight and weight gain. Significance was determined at p<0.05. Results: Mean 25[OH]D across pregnancy did not reach the established threshold for adequacy in pregnancy (63.3 + 19.5, 65.7 + 20.4, 65.9 + 24.4 nmol/L for trimester 1, 2 and 3, respectively). 1st trimester 25[OH]D levels were positively correlated with levels across pregnancy (p<0.001). 1st trimester 25[OH]D levels were negatively correlated with maternal early pregnancy weight (p<0.001) and maternal weight prior to birth (p